Technical Abstract:
The I locus in soybean is associated with seed coat pigmentation and contains three members of the chalcone synthase gene family, CHS4, CHS3, and CHS1. We sequenced and completely annotated BAC clone 104J7 which contains the I locus from soybean cultivar Williams 82 and found that the 10.91-kb CHS4, CHS3, CHS1 cluster is present as an exact invert repeat separated by 5.87 kb. This structure will allow for folding into multiple secondary structures that are hypothesized to induce deletions and affect the regulation of CHS. Genes present on this BAC in addition to the CHS genes, include: two unknown but expressed genes with homologs in Arabidopsis and rice, a RAB geranylgeranyl transferase type II beta subunit, and a beta-galactosidase. Several gene fragments or remnants were also detected that encode for: the carboxy end of a actin-related protein 2/3 complex 20 kDa subunit (ARC P20), a partial cation/hydrogen exchanger (CHX), the amino end of a subtilisin, two hypothetical proteins, a partial 40S ribosomal protein, and a partial thymidine kinase.